The man who is going to save the world is an ordinary-looking man. He's average in height, with an average face. He has blue eyes and sandy hair. He wears eyeglasses. He's forty-eight years old. He looks like the kind of guy you'd see buffing his car in the driveway or shopping for a new grill at Sears, a classic all-American Homo suburbanus, but in fact he is a former officer of the United States Navy with a Ph.D. in a fiendishly complicated type of engineering. He is low-key and unassuming, with a quiet midwestern sense of humor. He loves to surf and ski and cook and drink martinis and host large groups of people for long meals, spreading newspapers across the table to catch flying scraps of crab.

The man who is going to save the world leads high school field trips. He attends an Episcopal church where the priest is a woman. When he had a bigger house, he took in a series of foster children while they waited for adoption, eleven in all. He volunteers with a charity that teaches surfing to autistic children. One morning I watched him standing in the warm Carolina surf for hours, catching the kids as they fell off their surfboards. They went out scared and came back quivering with joy.

The man who is going to save the world is also a damn good father, a tendency that is at the heart of this world-saving business. His oldest child is an adorable high school senior named Zatha who is friendly and fearless, eager and full of questions, senior-class president, first-place winner in the statewide cross-country competition two years in a row. There's a glimpse of his parenting skills in the "racebook" he's using to encourage his son, Hans:

Team time trial, August 3, 2009, Monday.

The word Go was stated. The students took off, boys and girls. Kevin took the lead and you got behind him. Many thought, "Rookie mistake. Hans will fade," but Hans didn't slow down. His shadow continued to haunt Kevin all the way around the three-lap course. You had a time of 19:05. This is amazing, Hans. So a quote and a question:

"Effort and courage is not enough without purpose and direction." — JFK

Do you want to be number one this year and this season? If so, please contact Dad for secret training and coaching. — Dad

Eric Loewen talks the very same way when he is explaining patiently how he intends to save the world. The problem with saving the world is that change has no constituency. There is always a constituency for staying the same, but change is a risk. So change needs, as Loewen says, a "secret coach."

The next thing you should know is that Loewen's miracle technology is not some airy concept. It cost billions of dollars to develop. Some of the biggest companies in America spent ten years refining it under the close supervision of the U. S. government — before the program was shuttered and abandoned in a hasty political decision that makes Who Killed the Electric Car? look like a promotional film for General Motors.

Next, you must also consider the magnitude of the problem he's solving: a looming series of biblical disasters that include global warming, mass starvation, financial collapse, resource wars, and a long-term energy crisis that's much more desperate than most of us realize. Barring any spectacular new discoveries, assuming current trends in population and economic growth prevail, all the conventional oil in the world will be gone in about forty years. We can get maybe ten more if we suck dry oil sands and shale. We have enough natural gas to last about fifty years, enough coal to last between 150 and 300 years. But these fuels carry a heavy price. The emissions of coal plants alone carry, along with massive amounts of CO2, thousands of pounds of beryllium, manganese, selenium, lead, arsenic, and cadmium. They are 180 times more radioactive than the U. S. government's permissible level for the emissions of nuclear power plants. If we were to burn enough coal to survive, the result would be acid rain and acidifying oceans and pollution that kills fifty thousand Americans each year through diseases like asthma, bronchitis, and emphysema.

Which brings us to global warming. Most scientists now believe that the tipping point for global disaster is a CO2 level of 450 parts per million. We are now at just over 380 ppm and could pass 500 ppm in thirty years — in which case, in the words of Dr. James Hansen, the NASA scientist whose grim climate predictions have been coming true for the last thirty years, "We will hand our children a planet that has entered a long, chaotic, transient period with climate changes out of their control, as the planet heads inexorably toward an ice-free state." There are skeptics, of course, some of them quite distinguished, and a legitimate debate about just how bad things could get. But the bet is all or nothing, and an alarming number of the "cautious" are the same people who said cigarettes don't cause cancer, seat belts are a waste of money, and evolution is a hoax.

So what do we do? That's where this man comes in, because under most scenarios, solar and wind will never provide much more than 20 percent of our energy needs. Clean coal is a fiction, cap and trade ineffectual, and conservation almost as useless as Dick Cheney said it was — if we cut back on oil use by 10 percent, we will buy ourselves another four years. Hydropower provides only 2.5 percent, and we've already dammed up as many rivers as we are likely to dam. There's promise in biofuels, but at this point, all biofuels combined provide less than 2 percent of our energy needs, and we've already devoted more than a quarter of our annual corn crop to ethanol production. And nuclear power — which has the virtue of emitting no CO2 whatsoever — generates deadly nuclear waste that lasts forever and seems impossible to safely store.

The man who is going to save the world is giving a very speedy speech to the chamber of commerce of the town of Wilmington, North Carolina:

"Here's one of the problems Secretary Chu has running the Department of Energy: He has a lot of excess nuclear weapons that have a lot of plutonium that he has to figure out what to do with. He also has the problem of used nuclear fuel that is being stored in sites that are filling up. Then there's the problem of how we can generate enough clean power to satisfy the needs of the world. And the solution is..."

Here he is briefing Senator Lamar Alexander of Tennessee:

"So what is nuclear waste? It's still uranium! Right? It's 95 percent uranium. It's still usable. But we've got these evil things called transuranics, which is 1 percent of the total and 99 percent of the headache..."

And here he is in a small office outside Wilmington, scribbling formulas and figures on a whiteboard:

"Bad. So if I have a fast neutron, like these transuranics, the probability of achieving fission goes down. So the reason why we slow it down in a water reactor is, it gives us a higher probability of causing a fission. That allows us to start up this sort of reactor with only 3 percent of the fissile material. But with fast neutrons, I get more neutrons per fission."

Transuranics are highly radioactive elements like plutonium, typically regarded not as sources of energy but for their capacity to vaporize cities.

"But if I build a different kind of reactor that uses liquid sodium instead of water to slow things down, I can have a higher neutron speed and that stuff becomes a fuel. You just mix it in the crucible, put in the transuranics, put in some uranium, put in some zirconium, and you cast it into thin rods. That technology's been developed, it's easy to do, and you do it in a room about this size."

The miracle solution goes by different names: the sodium fast reactor, the integral fast reactor, the liquid-metal-cooled reactor. It burns nuclear waste, emits no CO2, and shuts itself down in an accident. We have enough fuel to power the whole world for tens of thousands of years. It will end global warming, and even if global warming is just another paranoid Armageddon fantasy, it will save us from the dying oceans and starvation and resource wars that are inevitable as the world's energy supply dwindles. It will unleash new industries and revitalize America's manufacturing industry.

Although he came late to the cause, Loewen has been preparing for it all his life. Raised in a Colorado mining town, he was studying science on a ski scholarship when he detoured into the Navy after his girlfriend dumped him, and he got selected for a program in nuclear engineering. Fast-forward five years and we find him standing watch on the U. S. S. Long Beach, the first surface ship in the nuclear navy. He is cruising the Persian Gulf, where Iranians just fired on an oil tanker flying a U. S. flag. Now a pair of Iranian warplanes are heading his way.

What am I doing here? he thought. I don't want to die in a stupid Iranian attack. I want to change the world for the better. I want to build nuclear reactors.

So he left the Navy and went back to graduate school, which led to a job at the National Laboratories in Idaho, a vast complex financed by the federal government and dedicated to futuristic technology. He began working on a fast reactor that used lead as a coolant.

For seven years he labored, writing scholarly articles, raising his family, taking in foster children, skiing the glorious Idaho powder. But he couldn't solve the problems of lead-cooled reactors. They had a nasty tendency to corrode.

Then he got two lucky breaks. First, he took a year's sabbatical and went to work in the office of Senator Chuck Hagel, where he helped push through groundbreaking global-warming legislation. That exercised his organizing skills and deepened his sense of alarm about the environmental crisis. Then he attended an Esquire magazine event and met an executive from General Electric.

In April 2006, GE hired him and handed him a giant file labeled "Compendium of S-PRISM Information." It was a revelation. "I was like, Wow, why didn't we build this?"

A month after plunging into the file, Loewen began meeting with officials from the U. S. Department of Energy and other veterans of the project, from the original project manager to the man who built the test reactor's electromagnetic pump. "He looked at me as a new greenhorn guy, a month on the job, and said, 'If you're serious about building this, go save that pump. And oh, by the way, they're knocking the building down in three months.' "

Gradually, he put the story together. The first glimmer of the fast-reactor concept began at the federal government's Argonne National Laboratory in 1951, when the sodium-cooled Experimental Breeder Reactor No. 1 powered four lightbulbs and proved that nuclear power was a real thing. In 1965, Argonne put into service Experimental Breeder Reactor No. 2, a demonstration project that ran successfully for thirty years. In 1971, Richard Nixon launched the Clinch River Breeder Reactor Project, putting together thousands of government and industry scientists in an effort to come up with a commercial prototype, but after twelve years, a mixture of technical problems, procurement scandals, and the relentless opposition of environmentalists finally led the Senate to kill it.

Then GE started rethinking things. One of Clinch River's problems was light-water envy. They were trying to power huge turbines that put out 1,000 megawatts. "So [GE] sat down and said, You know what, we're pretty good at making washing machines and jet engines in a factory and replicating them. Why don't we make a sodium-cooled reactor that's factory-built, modular, with passive safety and replicate that, instead of trying to scale up?"

Passive safety meant that it would shut itself off automatically instead of melting down. Replicability meant the reactor vessel couldn't be more than twenty feet in diameter, because that's the biggest you can ship down a rail line. So they would gang reactor modules together to power a single turbine. They named it the Power Reactor, Innovative Small Module, or PRISM.

At the time, it was a renegade idea. So what if PRISM could be mass-produced, plopped right next to every coal plant in the world, and hooked straight to their existing electric turbines just as fast as American steelworkers could crank them out? It was already so hard to get nuclear plants built, big seemed to be better. But the Department of Energy gave the project a green light, and GE put together a team that included giant companies like Westinghouse and Bechtel. They simplified it, made it safer, ran tests and reviews, and by 1986, proved the passive safety concept on Experimental Breeder Reactor No. 2. The design posed less of a proliferation risk than regular light-water reactors. By 1992, after spending $1 billion, they were ready to build a prototype.

Then Bill Clinton came into office and killed it. Maybe it was the lingering legacy of Three Mile Island, or Chernobyl, and the fear of proliferation. But by 2006, everything had changed. The consensus on global warming was rising, wars in the Middle East exposed the vulnerability of our oil supply, influential environmentalists like Patrick Moore and Stewart Brand began switching sides, and Republicans — who have always been more friendly to nuclear power — held sway in Washington. President Bush announced the Global Nuclear Energy Partnership, an ambitious research effort that linked twenty-one countries to "close the nuclear fuel cycle" and solve the waste problem. Soon afterward, the Department of Energy gave Loewen the green light.

It was time to dust off the PRISM.

Writing by himself at first, he started a "Design Control Document" that covered everything from the technical design to the business plan. Scavenging help wherever he could and sweetening the deal with surfing lessons, he hired an outside firm to do the 3-D modeling and got a twenty-year-old engineering intern to redesign the reactor vessel in a year of eighty-hour weeks. Meanwhile, as America's Secret Coach, he used his political savvy and personal charm to spread the excitement: inviting engineering students to workshops, giving lectures at the American Nuclear Society, flying to Vermont to spend a day pitching the lieutenant governor on an experimental PRISM reactor for the state university. With a millionaire Silicon Valley inventor named Steve Kirsch, who joined the cause after a fatal diagnosis convinced him to spend his last days saving the planet, Loewen traveled to Washington to pitch PRISM on Capitol Hill. Kirsch told me he first learned about the fast-reactor concept from a newsletter written by Dr. Hansen, the hero of An Inconvenient Truth. "I was intrigued because from Hansen's description, it sounded like we must be nuts for not pursuing this. If you discovered a machine that turned lead into gold, you'd think the government would exploit the machine for the good of the country."

Now the clock is ticking down. Shortly after taking office, President Obama stopped work on the proposed nuclear-waste storage facility at Yucca Mountain and put the brakes on the Global Nuclear Energy Partnership. Of the $39 billion in stimulus money given to the Department of Energy, not a single dollar went to nuclear. On the positive side, Energy Secretary Steven Chu has begun assembling a "blue ribbon" commission to study the energy alternatives and make a conceptual leap into the future — all of which turns up the dial on Loewen's sense of urgency. If he can find a way to sway Chu and Obama, to make them see that fast reactors are the only scalable answer to global warming, the world can still be saved. "To me the answer is simple," he says. "We have the solution. We don't need to study it anymore. And it's an American solution. It would revive our industrial spirit. Let's do it."

In this world full of critics, where fear and anxiety feed on ragged scraps of misinformation and nuclear power taps a mother lode of metaphysical angst, we overlook the facts. For example, at least forty-one workers have died in the production of modern wind turbines, but in sixty-one years commercial nuclear power hasn't killed a single man or woman in the United States. Even the disaster at Chernobyl killed just fifty-six people, and that was completely the fault of epic communist incompetence. But much of the environmental movement continues to hate nuclear power as an article of faith, and armchair scientists point to the difficulties of the fast nuclear plants in Russia and Japan, and the infinite armies of inertia simply avert their eyes.

To all these, Loewen's answer is a tour of the U. S. S. North Carolina, a World War II battleship anchored near downtown Wilmington.

First stop, the engine room, two big turbines and a screw painted the same green color as a high school boiler room. On to the rudder, with old-fashioned hydraulic arms that look like a giant bicycle wheel. To the combat information center where they plotted trajectories on what looks like a giant fuse box, to the navigation room where the dead-reckoning log still lies. Then he goes out onto the bridge, where he remembers the day he grabbed his binoculars and ran out to see the Iranian missiles coming to annihilate him. Why? "Because I wanted to see my fate," he says. The point is, PRISM isn't half as complicated — and they built a fleet of these battleships overnight. Now it's a fleet of nuclear reactors Loewen sees. "That's how I answer the naysayers who say we can't build this till 2040," he says.